1. Field of the Invention
This invention relates to mine stoppings for coal mines or the like to control the flow of air for mine ventilation.
2. Description of the Prior Art
Stopping devices are used to control and direct the flow of air through underground passageways and to seal off portions of a mine. The stoppings are often installed in mines so as to direct air flow to the working face and prevent loss of air flow through cross cuts and entries which are not being worked. In ventilating the mine, fresh air is delivered under pressure to the working face and often must travel a considerable distance between the mine opening and the face of the mine. If the stoppings separating the crosscuts and entries are not sufficiently air-tight, the losses will be such as to effectively reduce the velocity of the air at the mine face. It is not uncommon for a mine to lose more than half of its induced air through leaky stoppings and doors. Consequently, the dust and gases in the area being worked by the miners will not be effectively removed to the outside of the mine.
The construction and maintenance of mine stoppings is expensive and time consuming. Conventional stoppings consist of walls constructed of concrete block and cement, which are relatively difficult and costly to construct and maintain. For example, a typical coal mine stopping consists of about 160 concrete blocks, and at least one minimg car is usually required to transport construction materials significant distances down into the mine to erect one mine stopping. Furthermore, a substantial amount of time and manpower is also required to construct such a mine stopping since each of the concrete blocks have to be individually set in place and cemented.
The rigidity of a mine stopping of this type makes it susceptible to deformation by convergent ground movements or shock from explosve charges. Failure of the stopping is manifested by the formation of the aforementioned air leaks or, in the worst case, by a total collapse of the masonry structure, thereby requiring reconstruction of the stopping in the operational maintenance of the mine ventilation system. The elimination or reduction of stopping air leakage and of stopping failures is essential to the provision of a satisfactory ventilation efficiency in the mine, with resulting health and safety benefits to the miners.